Obviously, some combination of the two will be the most beneficial.
But, if you're pressed for time, it's almost always better to learn content. You'd have a better chance at answering most questions. Now, your ability to craft excellent responses might not be the greatest, but it sure won't be as bad as most make it. Learning the content gives structure to your understanding. And structure to your understanding will add structure to most of your responses.
A cool thing about the way we learn is also this - tasks that require some sort of prerequisite understanding that you don't have to perform that task takes a lot more brain power than you think. For instance, you'll come across a question and its suggested answer, and find it relatively more difficult to follow along than if you had studied some of the content first.
Again, a combination of the two will be the best. But if push comes to shove, content first (except maths).